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Asymptomatic adults at low risk for developing cardiovascular disease do not benefit from cardiac screening with electrocardiography, stress electrocardiography, or myocardial perfusion imaging, according to the American College of Physicians.

Point out that ACP task force members said that even if a cardiac abnormality is uncovered via screening, the most effective treatment may be adjustments in diet, exercise, and other "modifiable CHD risk factors" that would be recommended regardless of screening results.

Asymptomatic adults at low-risk for developing cardiovascular disease do not benefit from cardiac screening with electrocardiography, stress electrocardiography, or myocardial perfusion imaging, according to the American College of Physicians.

"Cardiac screening is likely to be particularly inefficient in adults at low risk for coronary heart disease (CHD) given the low prevalence and predictive values of testing in this population and the low likelihood that positive findings will affect treatment decisions," reported Roger Chou, MD, and colleagues from the ACP's High Value Task Force.

Asymptomatic, low-risk adults were defined as the patient population with an estimated 10-year risk of CHD events of <10%, they wrote in the Annals of Internal Medicine.

"These recommendations are based on the lack of evidence showing that screening improves clinical outcomes, unclear effects on risk reclassification and the use of risk-reducing therapies, and the relatively low prevalence of disease," they wrote.

The ACP task force performed a systematic review on their own 2011 cardiac screening guidelines, as well as recommendations from the U.S. Preventative Services Task Force (USPSTF), guidelines and standards from the American College of Cardiology and other professional societies, and articles about the various aspects of cardiac screening.

While abnormalities discovered via resting or exercise ECG were associated with an increased risk of subsequent cardiovascular events, they had no effect on clinical outcomes. Even after adjusting for traditional risk factors, pooled adjusted hazard ratios ranged from 1.4 to 2.1. The authors reported this was not enough to move a patient from a lower-risk into a higher-risk Framingham Risk Score category, meaning its effect on subsequent clinical treatment decisions would be marginal.

The authors said that even if a cardiac abnormality is uncovered via screening, the most effective treatment may be adjustments in diet, exercise and other "modifiable CHD risk factors" that would be recommended regardless of screening results.

They also noted that only a small number of patients may actually benefit from treatment, citing an example from the "well-conducted Coronary Artery Surgery Study." The study found that while coronary angiography showed that among patient undergoing the procedure for nonspecific chest pain, 40% of men and 24% of women had coronary atherosclerosis, but only 3% of men and 0.6% of women exhibited evidence of the disease that was severe enough to benefit from revascularization.

Low-risk patients being inappropriately screened via myocardial perfusion imaging (MPI) may be associated with increased risk for cancer from excess radiation, as well as the high probability of false-positive results, the task force members stated.

Not only do patients experience risks from initial screening but follow-up testing as well, they added. Angiography is associated with an effective radiation dose of 7 mSv, as well as a 1.7% risk for serious adverse events, including death, myocardial infarction, stroke, and arrhythmia. The use of angiography has also been questioned in a recent study, which found that more than 40% of patients meeting "appropriate" screening criteria did not actually have obstructive coronary artery disease.

Despite additional studies showing that stress MPI and echocardiography examinations do not meet appropriateness criteria, the use of these tests appears to be increasing, according to the task force. One study found ECG use jumped over a 10-year period (6.1% in 1999 to 11.3% in 2009), and a Consumer Reports study revealed 39% of asymptomatic adults without high blood pressure reported having an ECG in the past 5 years.

The ACP report cites a number of potential reasons for this overuse of cardiac screening, including potential reimbursement incentives. One study found greater relative increases in payments for MPIs to cardiologists than radiologists, which may be influencing their recommendations to patients. Other factors seemed to include fear of malpractice liability, underestimating screening harms, and overestimating the benefits of revascularization.

Patients' outsize enthusiasm for diagnostic screening may also play a role, as a number of patients are now opting for direct-to-consumer testing. "One study of cancer screening found that nearly three-quarters of respondents preferred a total-body computed tomographic scan over $1,000 in cash," the authors wrote. Another study showed similar unnecessary diagnostic testing for cancer.

The "Choosing Wisely" campaign from the American Board of Internal Medicine (ABIM) is attempting to educate clinicians about the potential harms of unnecessary screening.

"To be most effective, efforts to reduce the use of imaging should be multifocal and should address clinician behaviors, patient expectations, direct-to-consumer screening programs, and financial incentives," the report concluded.

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